Herbicidal composition and weeding method

ABSTRACT

The present invention relates to a herbicidal composition containing as active ingredients at least one organophosphorus compound and 3-substituted phenylpyrazole derivative of the general formula (I): ##STR1##  wherein R is --Y 1  R 3 , --Y 2  CH(R 4 )CO--OR 5 , --COOCH(R 4 )CO--Y 1  R 5  or --COOR 6  (R 3 , R 4 , R 5 , R 6 , Y 1  and Y 2  are specified groups), R 1  is a lower alkyl group, R 2  is a hydrogen atom, a lower alkyl group or a lower haloalkyl group, X 1  and X 2 , which may be the same or different, are halogen atoms, Y is --O--, --S--, --SO-- or --SO 2  --, and n is zero or 1!; and a weeding method using said composition.

This is a continuation of application Ser. No. 08/141,082, filed on Oct.26, 1993, which was abandoned upon the filing hereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a herbicidal composition containing as activeingredients at least one organophosphorous compound and a 3-substitutedphenylpyrazole derivative represented by the general formula (I):##STR2## wherein R is

    --Y.sup.1 R.sup.3

(wherein R³ is a lower alkyl group, a lower haloalkyl group, a loweralkenyl group or a lower alkynyl group, and Y¹ is --O-- or --S--),

    --Y.sup.2 CH(R.sup.4)CO--OR.sup.5

(wherein R⁴ is a hydrogen atom or a lower alkyl group, R⁵ is a hydrogenatom, a lower alkyl group, a lower haloalkyl group, a lower alkenylgroup or a lower alkynyl group, and Y² is --O--, --S-- or --NH--),

    --COOCH(R.sup.4)CO--Y.sup.1 R.sup.5

(wherein R⁴, R⁵ and Y¹ are as defined above), or

    --COOR.sup.6

(wherein R⁶ is a lower alkyl group, a lower alkenyl group or a loweralkynyl group), R¹ is a lower alkyl group, R² is a hydrogen atom, alower alkyl group or a lower haloalkyl group, X¹ and X², which may bethe same or different, are halogen atoms, Y is --O--, --S--, --SO-- or--SO₂ --, and n is zero or 1; and a weeding method using saidcomposition.

2. Related Art

The 3-substituted phenylpyrazole derivative of the general formula (I)is a compound described in Japanese Patent Unexamined Publication Nos.3-163063 and 4-211065 and were found to be useful as a herbicide.

The organophosphorus compound used in the present invention is awell-known herbicide, for example, N-(phosphonomethyl)glycine or a saltthereof which are described in Japanese Patent Unexamined PublicationNos. 47-39538 and 57-95994, 4-Hydroxy(methyl)phosphinoyl!-DL-homoalanine described in Japanese PatentPost-examined Publication No. 57-26564, or 4-Hydroxy(methyl)-phosphinoyl!-L-homoalanyl-L-alanyl-L-alanine describedin Japanese Patent Post-examined Publication No. 59-23282, etc.

Organophosphorus compounds are foliage applied herbicides widely used asnon-selective herbicides, but they exhibit initial effect slowly and arenot sufficiently effective against herbaceous weeds in developed leafstage or reproduction stage. Therefore, there is an eager desire for theadvent of a herbicide which exhibits herbicidal effect soon afterapplication and has a sufficient herbicidal effect also on theherbaceous weeds in developed leaf stage or reproductive stage.

SUMMARY OF THE INVENTION

The present inventors earnestly investigated for solving such problemsand consequently found that the simultaneous use of a 3-substitutedphenylpyrazole derivative of the above general formula (I) and at leastone organophosphorus compound gives fast-acting property and a wide weedcontrol spectrum and moreover brings about an excellent synergisticeffect at a dosage which is unexpectedly lower than a dosage requiredwhen each of the compounds is used alone, whereby the present inventionhas been accomplished.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the synergistic effect of a herbicidalcomposition (containing compound 19 and compound B) of the presentinvention by isobole analysis.

FIG. 2 is a graph showing the synergistic effect of a herbicidalcomposition (containing compound 19 and compound C) of the presentinvention by isobole analysis.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention relates to a herbicidal composition containing acompound of general formula (I) and at least one herbicidalorganophosphorus compound as active ingredients, and a weeding methodusing said composition.

Examples of the compound of the general formula (I) are given in Table 1but needless to say, they are not intended in any way to limit the scopeof the present invention. ##STR3##

                                      TABLE 1                                     __________________________________________________________________________    (Examples of compound of the above general formula in which R.sup.1 is        CH.sub.3 are given below.)                                                    No.                                                                              R            R.sup.2                                                                           X.sup.1                                                                          X.sup.2                                                                          (Y)n                                                                             Physical properties                              __________________________________________________________________________     1 OCH.sub.2 CH═CH.sub.2                                                                  CH.sub.3                                                                          Cl Cl S  nD 1.6131 (25.3° C.)                       2 OCH.sub.2 CH═CH.sub.2                                                                  CHF.sub.2                                                                         Cl Cl O  nD 1.5536 (28.4° C.)                       3 OCH.sub.2 CH═CH.sub.2                                                                  CHF.sub.2                                                                         F  Cl O  m.p. 63.7-64.1° C.                         4 SCH.sub.2 CH═CH.sub.2                                                                  CH.sub.3                                                                          Cl Cl S  paste                                             5 SCH.sub.2 CH═CH.sub.2                                                                  CHF.sub.2                                                                         Cl Cl O  m.p. 52.0-55.0° C.                         6 SCH.sub.2 CH═CH.sub.2                                                                  CHF.sub.2                                                                         F  Cl O  nD 1.5670 (17.9° C.)                       7 OCH.sub.2 C.tbd.CH                                                                         CH.sub.3                                                                          Cl Cl S  m.p. 71.5° C.                              8 OCH.sub.2 C.tbd.CH                                                                         CHF.sub.2                                                                         Cl Cl O  m.p. 84.0° C.                              9 OCH.sub.2 C.tbd.CH                                                                         CHF.sub.2                                                                         F  Cl O  m.p. 98.0-98.1° C.                        10 SCH.sub.2 C.tbd.CH                                                                         CH.sub.3                                                                          Cl Cl S  m.p. 94.5° C.                             11 SCH.sub.2 C.tbd.CH                                                                         CHF.sub.2                                                                         Cl Cl O  m.p. 127-129° C.                          12 SCH.sub.2 C.tbd.CH                                                                         CHF.sub.2                                                                         F  Cl O  m.p. 82.8° C.                             13 OCH.sub.2 COOCH.sub.3                                                                      CH.sub.3                                                                          Cl Cl S  m.p. 126.2° C.                            14 OCH.sub.2 COOCH.sub.3                                                                      CHF.sub.2                                                                         Cl Cl O  m.p. 119.8° C.                            15 OCH.sub.2 COOCH.sub.3                                                                      CHF.sub.2                                                                         Cl Br O  m.p. 133.8° C.                            16 OCH.sub.2 COOCH.sub.3                                                                      CHF.sub.2                                                                         F  Cl O  m.p. 122.8-123.1° C.                      17 OCH.sub.2 COOC.sub.2 H.sub.5                                                               CH.sub.3                                                                          Cl Cl S  m.p. 106.5° C.                            18 OCH.sub.2 COOC.sub.2 H.sub.5                                                               CHF.sub.2                                                                         Cl Cl O  m.p. 102.3° C.                            19 OCH.sub.2 COOC.sub.2 H.sub.5                                                               CHF.sub.2                                                                         F  Cl O  m.p. 127.6° C.                            20 OCH.sub.2 COOC.sub.3 H.sub.7 -n                                                            CHF.sub.2                                                                         Cl Cl O  m.p. 89.7° C.                             21 OCH.sub.2 COOC.sub.3 H.sub.7 -n                                                            CHF.sub.2                                                                         F  Cl O  m.p. 97.6-97.8° C.                        22 OCH.sub.2 COOC.sub.3 H.sub.7 -i                                                            CHF.sub.2                                                                         Cl Cl O  m.p. 106.0° C.                            23 OCH.sub.2 COOC.sub.3 H.sub.7 -i                                                            CHF.sub.2                                                                         F  Cl O  m.p. 120.3-120.5° C.                      24 OCH.sub.2 COOCH.sub.2 CH═CH.sub.2                                                      CHF.sub.2                                                                         Cl Cl O  m.p. 84.7° C.                             25 OCH.sub.2 COOCH.sub.2 CH═CH.sub.2                                                      CHF.sub.2                                                                         F  Cl O  m.p. 98.2-89.4° C.                        26 OCH.sub.2 COOCH.sub.2 C.tbd.CH                                                             CHF.sub.2                                                                         Cl Cl O  m.p. 119.6° C.                            27 OCH.sub.2 COOCH.sub.2 C.tbd.CH                                                             CHF.sub.2                                                                         F  Cl O  m.p. 99.0° C.                             28 OCH(CH.sub.3)COOH                                                                          CH.sub.3                                                                          Cl Cl S  m.p. 191-194° C.                          29 OCH(CH.sub.3)COOCH.sub.3                                                                   CH.sub.3                                                                          Cl Cl S  m.p. 90-93° C.                            30 OCH(CH.sub.3)COOCH.sub.3                                                                   CHF.sub.2                                                                         F  Cl O  m.p. 95.6° C.                             31 OCH(CH.sub.3)COOC.sub.2 H.sub.5                                                            CH.sub.3                                                                          Cl Cl S  nD 1.5763 (28.8° C.)                      32 OCH(CH.sub.3)COOC.sub.2 H.sub.5                                                            CHF.sub.2                                                                         Cl Cl O  nD 1.5238 (25.7° C.)                      33 OCH(CH.sub.3)COOC.sub.2 H.sub.5                                                            CHF.sub.2                                                                         Cl Br O  nD 1.5396 (20.8° C.)                      34 OCH(CH.sub.3)COOC.sub.2 H.sub.5                                                            CHF.sub.2                                                                         F  Cl O  m.p. 67.0-67.2° C.                        35 OCH(CH.sub.3)COOC.sub.3 H.sub.7 -i                                                         CH.sub.3                                                                          Cl Cl S  m.p. 87-90° C.                            36 SCH(CH.sub.3)COOCH.sub.3                                                                   CHF.sub.2                                                                         Cl Cl O  nD 1.5654 (19.8° C.)                      37 SCH(CH.sub.3)COOCH.sub.3                                                                   CHF.sub.2                                                                         F  Cl O  nD 1.5494 (25.0° C.)                      38 SCH(CH.sub.3)COOC.sub.2 H.sub.5                                                            CHF.sub.2                                                                         Cl Cl O  nD 1.5565 (28.0° C.)                      39 SCH(CH.sub.3)COOC.sub.2 H.sub.5                                                            CHF.sub.2                                                                         F  Cl O  nD 1.5328 (18.0° C.)                      40 NHCH(CH.sub.3)COOC.sub.2 H.sub.5                                                           CH.sub.3                                                                          Cl Cl S  m.p. 144.2° C.                            41 NHCH(CH.sub.3)COOC.sub.2 H.sub.5                                                           CH.sub.3                                                                          Cl Cl S  paste                                            42 NHCH(CH.sub.3)COOC.sub.2 H.sub.5                                                           CHF.sub.2                                                                         Cl Cl O  nD 1.5371 (23.4° C.)                      43 NHCH(CH.sub.3)COOC.sub.2 H.sub.5                                                           CHF.sub.2                                                                         F  Cl O  nD 1.5264 (26.6° C.)                      44 COOCH.sub.2 COOCH.sub.3                                                                    CHF.sub.2                                                                         Cl Cl O  m.p. 74.4° C.                             45 COOCH.sub.2 COOCH.sub.3                                                                    CHF.sub.2                                                                         F  Cl O  nD 1.5350 (27.3° C.)                      46 COOCH.sub.2 COSCH.sub.3                                                                    CHF.sub.2                                                                         Cl Cl O                                                   47 COOCH.sub.2 COSCH.sub.3                                                                    CHF.sub.2                                                                         F  Cl O                                                   48 COOCH.sub.2 COOC.sub.2 H.sub.5                                                             CHF.sub.2                                                                         Cl Cl O  m.p. 57.2° C.                             49 COOCH.sub.2 COOC.sub.2 H.sub.5                                                             CHF.sub.2                                                                         F  Cl O  nD 1.5362 (23.4° C.)                      50 COOCH.sub.2 COSC.sub.2 H.sub.5                                                             CHF.sub.2                                                                         Cl Cl O  nD 1.5763 (20.7° C.)                      51 COOCH.sub.2 COSC.sub.2 H.sub.5                                                             CHF.sub.2                                                                         F  Cl O  nD 1.5536 (27.3° C.)                      52 COOCH.sub.2 COOC.sub.3 H.sub.7 -i                                                          CHF.sub.2                                                                         Cl Cl O  nD 1.5289 (24.0° C.)                      53 COOCH.sub.2 COOC.sub.3 H.sub.7 -i                                                          CHF.sub.2                                                                         F  Cl O                                                   54 COOCH.sub.2 COOC.sub.3 H.sub.7 -i                                                          CHF.sub.2                                                                         Cl Cl O  nD 1.5684 (20.2° C.)                      55 COOCH.sub.2 COOC.sub.3 H.sub.7 -i                                                          CHF.sub.2                                                                         F  Cl O                                                   56 COOCH.sub.2 COOCH.sub.2 CH═CH.sub.2                                                    CHF.sub.2                                                                         Cl Cl O  m.p. 45.4° C.                             57 COOCH.sub.2 COOCH.sub.2 CH═CH.sub.2                                                    CHF.sub.2                                                                         F  Cl O                                                   58 COOCH.sub.2 COOCH.sub.2 C.tbd.CH                                                           CHF.sub.2                                                                         Cl Cl O  m.p. 79.3° C.                             59 COOCH.sub.2 COOCH.sub.2 C.tbd.CH                                                           CHF.sub.2                                                                         F  Cl O                                                   60 COOCH(CH.sub.3)COOCH.sub.3                                                                 CHF.sub.2                                                                         Cl Cl O  nD 1.5370 (25.7° C.)                      61 COOCH(CH.sub.3)COOCH.sub.3                                                                 CHF.sub.2                                                                         F  Cl O  nD 1.5314 (23.0° C.)                      62 COOCH(CH.sub.3)COOC.sub.2 H.sub.5                                                          CHF.sub.2                                                                         Cl Cl O  nD 1.5672 (26.0° C.)                      63 COOCH(CH.sub.3)COOC.sub.2 H.sub.5                                                          CHF.sub.2                                                                         F  Cl O  nD 1.5212 (14.1° C.)                      64 COOCH.sub.2 C.tbd.CH                                                                       CHF.sub.2                                                                         Cl Cl O  m.p. 78.5° C.                             65 COOCH.sub.3  CHF.sub.2                                                                         Cl Cl O  m.p. 63.9° C.                             66 COOCH.sub.3  CHF.sub.2                                                                         F  Cl O  nD 1.5430 (17.0° C.)                      67 COOC.sub.2 H.sub.5                                                                         CH.sub.3                                                                          Cl Cl S  nD 1.6029 (20.1° C.)                      68 COOC.sub.2 H.sub.5                                                                         CHF.sub.2                                                                         Cl Cl O  nD 1.5446 (26.8° C.)                      69 COOC.sub.2 H.sub.5                                                                         CHF.sub.2                                                                         F  Cl O  nD 1.5320 (21.0° C.)                      70 OCH.sub.2 CH═CH.sub.2                                                                  CHF.sub.2                                                                         Cl Cl NH m.p. 80.6° C.                             71 OCH.sub.2 C.tbd.CH                                                                         CHF.sub.2                                                                         Cl Cl NH m.p. 118.9° C.                            72 OCH.sub.2 COOCH.sub.3                                                                      i-C.sub.3 H.sub.7                                                                 Cl Cl -- paste                                            73 OCH.sub.2 CH═CH.sub.2                                                                  i-C.sub.3 H.sub.7                                                                 Cl Cl -- paste                                            74 OCH.sub.2 C.tbd.CH                                                                         i-C.sub.3 H.sub.7                                                                 Cl Cl -- paste                                            75 SCH.sub.2 COOCH.sub.3                                                                      t-C.sub.4 H.sub.9                                                                 Cl Cl -- paste                                            76 OCH.sub.2 CH═CH.sub.2                                                                  CH.sub.2 Br                                                                       Cl Cl -- paste                                            __________________________________________________________________________

As the herbicidal organophosphorus compound, i.e., the other activeingredient used in the present invention, there can be used one or morecompounds selected from the group consisting ofN-(phosphonomethyl)glycine or a salt thereof, such asN-(phosphonomethyl)glycine isopropylammonium salt (hereinafter referredto as "compound A") or N-(phosphonomethyl)glycine trimethyl-sulfoniumsalt (hereinafter referred to as "compound B"); 4-hydroxy(methyl)phosphinoyl!-DL-homoalanine or a salt thereof, such as 4-hydroxy(methyl)phosphinoyl!-DL-homoalanine ammonium salt (hereinafterreferred to as "compound C"); 4-hydroxy(methyl)phosphinoyl!-L-homoalanyl-L-alanyl-L-alanine or a saltthereof, such as 4-hydroxy(methyl)phosphinoyl!-L-homoalanyl-L-alanyl-L-alanine sodium salt(hereinafter referred to as "compound D"); etc. The organophosphoruscompounds exemplified above are not intended in any way to limit thescope of the present invention.

For applying the herbicidal composition of the present invention, it maybe prepared into suitable forms according to an ordinary manner forpreparation of agrochemicals, depending on purposes. For example, saidcomposition is blended with one or more materials selected from thegroup consisting of solid carriers, liquid carriers and surfactants, andoptionally adjuvants, etc. and prepared into a preparation form such aswater dispersible granules, a wettable powder, dust, a suspensionconcentrate, a soluble concentrate, or the like.

The active ingredients of the herbicidal composition of the presentinvention may be blended in optional proportions, depending on the typeof formulation. The blending proportions of the active ingredients insaid composition may be properly chosen in the following range: theproportion of organophosphorus compound is 0.01 to 1,000 parts byweight, preferably 1 to 500 parts by weight, per part by weight of3-substituted phenylpyrazole derivative of the general formula (I).

The herbicidal composition of the present invention is useful as anon-selective herbicidal composition. The composition has fast-actingproperty which the organophosphorus compound does not have, by virtue ofthe simultaneous use of 3-substituted phenylpyrazole derivative and theorganophosphorus compound, and moreover the composition permitsreduction of the dosage because the simultaneous use brings about asynergistic effect which cannot be expected when each of the two agentsis used alone.

The herbicidal composition of the present invention is usefulparticularly as a non-selective herbicide. The composition can be used,for example, for controlling weeds emerging in non-crop lands such asroads, building sites, railbeds, parks and playgrounds, and groundcovering weeds in orchards, managed forests, forests, tame forests, etc.Furthermore, the composition can be used also as a weed management agentfor levees of paddy fields and a clean up herbicide for fallow fields,and upland fields before planting. The composition is effective incontrolling, for example, dicotyledons such as asiatic dayflower(Commelina communis), tufted knotweed (Polygonum longisetum), sweetscabious (Erigeron annuus), horseweed (Erigeron canadensis), shepherd'spurse (Capsella bursa-pastoris), pale persicaria (Polygonumlapathifolium), livid amaranth (Amaranthus lividus), cudweed (Gnaphaliumaffine), three seeded copper leaf (Acalypha australis), slender amaranth(Amaranthus varidis), chickweed (Stellaria media), etc.; gramineousweeds such as large crabgrass (Digitaria adscendens), barnyard grass(Echinochloa crus-galli), annual bluegrass (Poa annua), water foxtail(Alopecurus aequalis), etc.; and perennial weeds such as curly dock(Rumex juponicus), mugwort (Artemisia princeps), field horsetail(Equisetum arvense), asiatic plantain (Plantago asiatica), philadelphiafleabane (Erigeron philadelphicus), dandelion (Taraxacum officinale),cogon grass (Imperata cylindrica), eulalia grass (Miscanthus sinensis),sorrel vine (Cayratia japonica), etc.

The present invention is applicable not only to the above places andweeds but also to all places and objective weeds for controllingundesirable weeds.

Although the herbicidal composition of the present invention is appliedpreferably during the early-post emergence or vegetative growth stage ofweeds, its application time is not limited to these periods.

The dosage of the herbicidal composition of the present invention may bechosen in the range of 1 to 5,000 g (in terms of the active ingredients)per 10 ares.

When a compound such as2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid (commonname: imazapyr), methyl sulfanilylcarbamate (common name: asulam) or thelike is used together with the 3-substituted phenylpyrazole derivativeof the general formula (I) in place of the organophosphorus compound,i.e., one of the active ingredients used in the present invention, therecan be obtained the same effect as that obtained by using theorganophosphorus compound together with said derivative.

EXAMPLES

Typical examples of the present invention are described below but shouldnot be construed as limiting the scope of the invention.

In the examples, parts are all by weight.

Example 1

    ______________________________________                                        Compound 19             0.2    part                                           Compound C              18.5   parts                                          Genapol LRD (mfd. by Hoechst AG)                                                                      20.0   parts                                          Glauber's salt          20.0   parts                                          Clay                    16.3   parts                                          Bentonite               10.0   parts                                          Hydrated silicic acid   10.0   parts                                          Calcium ligninsulfonate 5.0    parts                                          Total                   100.0  parts                                          ______________________________________                                    

Granular wettable powder was prepared by mixing the predeterminedamounts of compound 19, compound C, Glauber's salt, clay, bentonite andhydrated silicic acid uniformly, placing the resulting mixed powder in afluidized-bed granulator, and spraying the mixed powder with an aqueoussolution containing the predetermined amounts of Genapol LRD and calciumligninsulfonate, followed by granulation and drying.

Example 2

    ______________________________________                                        Compound 19            0.2    part                                            Compound C             18.5   parts                                           Pluronic L-64 (mfd. by Asahi                                                                         5.0    parts                                           Denka Co. Ltd.)                                                               Sodium alkylbenzensulfonate                                                                          2.0    parts                                           Methylnaphtalene       10.0   parts                                           Water                  64.3   parts                                           Total                  100.0  parts                                           ______________________________________                                    

An aqueous suspension concentrate was prepared by mixing thepredetermined amounts of compound 19 and methylnaphthalene to obtain asolution, adding compound C, Pluronic L-64, Sodium alkylbenzensulfonateand water to the solution, and mixing them uniformly by means of ahigh-speed agitator.

Example 3

    ______________________________________                                        Compound 19            0.2    part                                            Compound B             38.0   parts                                           Pluronic L-64 (mfd. by Asahi                                                                         5.0    parts                                           Denka Co. Ltd.)                                                               Sodium alkylbenzenesulfonate                                                                         2.0    parts                                           Methylnaphtalene       10.0   parts                                           Water                  44.8   parts                                           Total                  100.0  parts                                           ______________________________________                                    

An aqueous suspension concentrate was prepared by mixing thepredetermined amounts of compound 19 and methylnaphthalene to obtain asolution, adding compound B, Pluronic L-64, sodium alkylbenzenesulfonateand water to the solution, and mixing them uniformly by means of ahigh-speed agitator.

Example 4

    ______________________________________                                        Compound 19             0.2    part                                           Compound C              18.5   parts                                          Hitenol No. 8 (mfd. by Dai-ichi                                                                       3.0    parts                                          Kogyo Seiyaku Co., Ltd.)                                                      Calcium ligninsulfonate 3.0    parts                                          Carplex #80 (mfd. by Shionogi &                                                                       5.0    parts                                          Co., Ltd.)                                                                    Clay                    70.3   parts                                          Total                   100.0  parts                                          ______________________________________                                    

A wettable powder was prepared by mixing uniformly and grinding theabove ingredients.

Example 5

    ______________________________________                                        Compound 19             0.2    part                                           Compound B              38.0   parts                                          Hitenol No. 8 (mfd. by Dai-ichi                                                                       3.0    parts                                          Kogyo Seiyaku Co., Ltd.)                                                      Calcium ligninsulfonate 3.0    parts                                          Carplex #80 (mfd. by Shionogi &                                                                       5.0    parts                                          Co., Ltd.)                                                                    Clay                    50.8   parts                                          Total                   100.0  parts                                          ______________________________________                                    

A wettable powder was prepared by mixing uniformly and grinding theabove ingredients.

Test Example 1

Synergistic-effect test on compositions of the present invention

A pot with a diameter of 12 cm and a height of 11 cm was filled withupland soil (sandy loam) and seeded with barnyard grass (Echinochloacrus-galli) so as to adjust the depth of covering soil to 0.5 cm, andthe barnyard grass was grown in a greenhouse.

When the barnyard grass was grown to a leaf stage of 3 and a height of10 cm in a test co-using compound B or a leaf stage of 5 and a height of15 cm in a test co-using compound C, a predetermined amount of eachherbicidal composition of the present invention was diluted with waterand the dilution was sprayed from above uniformly on the whole surfacesof the stem and leaves in a spray volume of 1,000 liters per hectare bythe use of a small-sized sprayer.

On the 10th day after the spraying, the degree of growth of theabove-ground part of surviving barnyard grass plants was visually judgedin the range of zero (ineffective) to 100 (complete kill) by comparisonwith that on the untreated plot.

The test results obtained in the composition of compound 19 and B orcompound 19 and C are shown in Table 2 and Table 3, respectively.

                  TABLE 2                                                         ______________________________________                                                   Amount of compound 19 as active                                               ingredient (g/ha)                                                             0   3.125  6.25   12.5 25.0 50.0 100.0                             ______________________________________                                        Amount    0       0    30   50   50   80   85   90                            of       125     40    40   50   60   85   95                                 compound 250     50    60   60   70   90   98                                 B as     500     60    70   70   80   95   99                                 active   1000    70    80   90   95   98   100                                ingredi- 2000    90    95   98   99   100  100                                ent                                                                           (g/ha)                                                                        ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                                   Amount of compound 19 as active                                               ingredient (g/ha)                                                             0   3.125  6.25   12.5 25.0 50.0 100.0                             ______________________________________                                        Amount   0        0    40   50   60   70   80   90                            of       62.5    50    50   60   60   90   95                                 compound 125     60    70   70   85   95   98                                 C as     250     80    85   90   95   98   99                                 active   500     90    95   95   98   99   100                                ingredi- 1000    98    98   98   98   100  100                                ent                                                                           (g/ha)                                                                        ______________________________________                                    

The above results are shown in the drawings for facilitating theunderstanding.

FIG. 1 shows a constant-effect curve drawn on the basis of theherbicidal effect on barnyard grass shown in Table 2 in the testexample.

The axis of abscissa refers to the amount (g/ha) of compound 19 asactive ingredient and the axis of ordinate to the amount (g/ha) ofcompound B as active ingredient.

The expected ED 90 isobole of additive effect is shown in the brokenline and ED 90 isobole of the combination between compound 19 andcompound B obtained in practice is shown in the solid line.

Similarly, the synergistic effect of the herbicidal composition(containing compound 19 and compound C) of the present invention isshown in FIG. 2.

As shown in FIG. 1 and FIG. 2, the herbicidal compositions of thepresent invention have synergistic effect clearly.

What is claimed is:
 1. A herbicidal composition comprising as activeingredients a synergistic effective amount of at least oneorganophosphorous compound and a synergistic effective amount of a3-substituted phenylpyrazole derivative represented by the generalformula (I): ##STR4## wherein R is

    --Y.sup.1 R.sup.3

(wherein R³ is a lower alkyl group, a lower haloalkyl group, a loweralkenyl group or a lower alkynyl group, and Y¹ is --O-- or --S--),

    --Y.sup.2 CH(R.sup.4)CO═OR.sup.5

(wherein R⁴ is a hydrogen atom or a lower alkyl group, R⁵ is a hydrogenatom, a lower alkyl group, a lower haloalkyl group, a lower alkenylgroup or a lower alkynyl group, and Y² is --O--, --S-- or --NH--),

    --COOCH(R.sup.4)CO--Y.sup.1 R.sup.5

(wherein R⁴, R⁵ and Y¹ are as defined above), or

    --COOR.sup.6

(wherein R⁶ is a lower alkyl group, a lower alkenyl group or a loweralkynyl group), R¹ is a lower alkyl group, R² is a hydrogen atom, alower alkyl group or a lower haloalkyl group, X¹ and X², which may bethe same or different, are halogen atoms, Y is --O--, --S--, --SO-- or--SO₂ --, and n is zero or
 1. 2. A herbicidal composition according toclaim 1, wherein the organophosphorus compound is selected from thegroup consisting of N-(phosphonomethyl)glycine or a salt thereof, 4-hydroxy (methyl)phosphinoyl!-DL-homoalanine or a salt thereof, 4-hydroxy(methyl)phosphinoyl!-L-homoalanyl-L-alanyl-L-alanine or a saltthereof.
 3. A herbicidal composition according to claim 2, wherein theorganophosphorus compound is contained in an amount of 0.01 to 1,000parts by weight per part by weight of the 3-substituted phenylpyrazolederivative of the general formula (I).
 4. A herbicidal compositionaccording to claim 3, wherein the herbicidal composition is anon-selective herbicide.
 5. A method for controlling weeds whichcomprises applying a herbicidal composition in a dosage chosen in therange of 1 g to 5 kg (in terms of the active ingredients of thecomposition) per 10 ares for controlling undesirable weeds, saidherbicidal composition comprising as active ingredients a synergisticeffective amount of at least one organophosphorous compound and asynergistic effective amount of a 3-substituted phenylpyrazolederivative represented by the general formula (I): ##STR5## wherein R is

    Y.sup.1 R.sup.3

(wherein R³ is a lower alkyl group, a lower haloalkyl group, a loweralkenyl group or a lower alkynyl group, and Y¹ is --O-- or --S--),

    --Y.sup.2 CH(R.sup.4)CO--OR.sup.5

(wherein R⁴ is a hydrogen atom or a lower alkyl group, R⁵ is a hydrogenatom, a lower alkyl group, a lower haloalkyl group, a lower alkenylgroup or a lower alkynyl group, and Y² is --O--, --S-- or --NH--),

    --COOCH(R.sup.4)CO--Y.sup.1 R.sup.5

(wherein R⁴, R⁵ and Y¹ are as defined above), or

    --COOR.sup.6

(wherein R⁶ is a lower alkyl group, a lower alkenyl group or a loweralkynyl group), R¹ is a lower alkyl group, R² is a hydrogen atom, alower alkyl group or a lower haloalkyl group, X¹ and X², which may bethe same or different, are halogen atoms, Y is --O--, --S--, --SO-- or--SO₂ --, and n is zero or
 1. 6. A method for controlling weedsaccording to claim 5, wherein the organophosphorus compound is selectedfrom the group consisting of N-(phosphonomethyl)glycine or a saltthereof, 4- hydroxy(methyl)phosphinoyl!-DL-homoalanine or a saltthereof, 4- hydroxy(methyl)phosphinoyl!-L-homoalanyl-L-alanyl-L-alanineor a salt thereof.
 7. A herbicidal composition according to claim 2,wherein the organophosphorus compound is contained in an amount of 1 to500 parts by weight per part by weight of the 3-substitutedphenylpyrazole derivative of the general formula (I).
 8. A method forcontrolling weeds which comprises the steps of applying a herbicidalcomposition in a dosage chosen in the range of 1 g to 5 kg, in terms ofthe active ingredients of the composition, per 10 ares for controllingundesirable weeds, said herbicidal composition comprising as activeingredients at least one herbicidal organophosphorus compound at adosage insufficient to control weeds as a sole active ingredient and asynergistic effective amount of a 3-substituted phenylpyrazolederivative represented by the formula (I): ##STR6## wherein R is

    --Y.sup.1 R.sup.3

wherein R³ is a lower alkyl group, a lower haloalkyl group, a loweralkenyl group or a lower alkynyl group, and Y¹ is --O-- or --S--,

    --Y.sup.2 CH(R.sup.4)CO--OR.sup.5

wherein R⁴ is a hydrogen atom, or a lower alkyl group, R⁵ is a hydrogenatom, a lower alkyl group, a lower haloalkyl group, a lower alkenylgroup or a lower alkynyl group, and Y² is --O--, --S-- or --NH--,

    --COOCH(R.sup.4)CO--Y.sup.1 R.sup.5

wherein R⁴, R⁵, and Y¹ are as defined above, or

    --COOR.sup.6

wherein R⁶ is a lower alkyl group, a lower alkenyl group or a loweralkynyl group, R¹ is a lower alkyl group, R² is a hydrogen atom, a loweralkyl group or a lower haloalkyl group, X¹ and X², which may be the sameor different, are halogen atoms, Y is --O--, --S--, --SO-- or --SO₂ --,and n is zero or 1.